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ghazizadeh-ehsaee--ali
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Design and Implementation of an Optical Intrinsic Signal Imaging System for Brain by Using Intensity Magnification Algorithm
, M.Sc. Thesis Sharif University of Technology ; Fardmanesh, Mahdi (Supervisor) ; Ghazizadeh Ehsaee, Ali (Supervisor)
Abstract
In many neuroscience studies, the aim is to investigate the functional role of a population of neurons in response to a certain stimulus. Electrophysiology methods usually can only record from a small population of neurons and this is not sufficient for studying functional properties of the cortex. An alternative is to use functional neuroimaging methods. However, some of these methods are expensive and also they do not offer suitable spatial and temporal resolutions. Optical imaging systems can solve these problems because they are low-cost, easy to design, and also have good temporal and spatial resolutions. These systems can generate functional maps from the brain. In this study, a...
Effect of Reward Training on Visual Representation of Objects in the Brain
, M.Sc. Thesis Sharif University of Technology ; Ghazizadeh, Ali (Supervisor)
Abstract
Sight is probably our most important sense. Every day, humans are exposed to many visual stimuli in their surroundings. The human brain is able to identify and prioritize important and valuable stimuli and memorize them. Identifying and remembering these valuable stimuli is vital to meeting the needs and maintaining survival. The aim of the proposed research is to find the effect of reward learning on the coding of visual objects in the human brain. Previous results have shown that long-term reward-object association make valuable objects more recognizable behaviorally. Studies have also shown that visual stimuli and the pattern of activity of primary visual cortex neurons are closely...
Low-cost, Non-infrared, MRI-compatible Eye Tracker for Research
, M.Sc. Thesis Sharif University of Technology ; Ghazizadeh, Ali (Supervisor)
Abstract
Looking for eye paths is widely used in various research and even commercial areas, Eye trackers that are used commercially today do this by using infrared transmitters and receivers. As the speed and performance of the processors advanced, many efforts have been made to create an eye-tracking device using visible light without any movement restrictions for the subject, and efforts to increase the accuracy and speed of sampling are still ongoing; The initial methods proposed in this area are feature-based, but newer papers and researches have used Deep learning methods to do this. The commonly used methods for eye tracking in visible light are three main steps: 1. Fetching frames from the...
Design and Implementation of Remote Eye Tracking Device on FPGA and Tolerated to Head Movements
, M.Sc. Thesis Sharif University of Technology ; Ghazizadeh, Ali (Supervisor)
Abstract
The Eye Tracker is a device that measures eye movements and can obtain user’s gaze point. This device has many applications, including research, functional, diagnosis and treatment. Our goal is implementation of a remote video-oculography based eye tracker that tolerates head movements, so that the user can capture his eye movement data accurately and effortlessly. It is obvious that a good eye tracker device should operate with high frame rate, which means doing large amount of calculations in a short while. We solved this problem with FPGA device by dividing the problem into five parts: eye localization, glint detection, pupil center detection, 2D mapping gaze detection and 3D model gaze...
Design and Implementation of True Time Delay (TTD) Circuits in 0.18μm CMOS for Transceiver Module Application
, Ph.D. Dissertation Sharif University of Technology ; Medi, Ali (Supervisor)
Abstract
In order to improve the performance of radar systems, encouraging the movement towards multifunctional applications, wider frequency span is required to be considered for phased array systems constituting radars. The conventional approach of phase shifting is not applicable to wideband phased array system, and the need for phased array systems based on time delay is apparent. In active phased array systems where a transceiver module is placed before each radiating element, the task of controlling the delay and gain variation of each path is assigned to individual core chips residing in the transceiver modules. A typical core chip consists of several amplifying blocks along, with delay and...
Robust zero watermarking for still and similar images using a learning based contour detection
, Article Communications in Computer and Information Science ; Vol. 427, issue , Sep , 2014 , p. 13-22 ; Jamzad, M ; Sharif University of Technology
2014
Abstract
Digital watermarking is an efficacious technique to protect the copyright and ownership of digital information. Traditional image watermarking algorithms embed a logo in the image that reduces its visual quality. A new approach in watermarking called zero watermarking doesn’t need to embed a logo in the image. In this algorithm we find a feature from the main image and combine it with a logo to obtain a key. This key is securely kept by a trusted authority. In this paper we show that we can increase the robustness of digital zero watermarking by a new counter detection method in comparison to Canny Edge detection and morphological dilatation that is mostly used by related works. Experimental...
Extracting Appropriate Features for Zero Watermarking of Similar Images for Ownership Protection
, M.Sc. Thesis Sharif University of Technology ; Jamzad, Mansour (Supervisor)
Abstract
Digital watermarking is an efficacious technique to protect the copyright and ownership of digital information. Traditional image watermarking algorithms embed a logo in the image that could reduce its visual quality. A new approach in watermarking called zero watermarking doesn’t need to embed a logo in the image. In this algorithm we find a feature from the main image and combine it with a logo to obtain a key. This key is securely kept by a trusted authority. In this thesis we show that we can increase the robustness of digital zero watermarking by a new counter detection method in comparison to Canny Edge detection and morphological dilatation that is mostly used by related works....
Extension and Comparing the PSTH and ICA in Order to Extract Information from Neural Point Processes
, Ph.D. Dissertation Sharif University of Technology ; Jahed, Mehran (Supervisor) ; Ghazizadeh, Ali (Co-Supervisor)
Abstract
The quantity and quality of information extracted from the brain, in addition to data collection methods, is also related to the statistical tools used. As extracting maximum information in both temporal and spatial dimension require electrophysiological approaches on the physical side, the statistical methods should be optimized to that end, on the theoretical side. The time histogram method is the most basic tool for capturing a time-dependent rate of neuronal spikes. Generally, in the neurophysiological literature, the bin size that critically determines the goodness of the fit of the time histogram to the underlying spike rate has been subjectively selected by individual researchers....
Analysis and Comparison of the Role of SNr and vlPFC in Value Learning and Memory and Value Guided Saccade
, M.Sc. Thesis Sharif University of Technology ; Ghazizadeh, Ali (Supervisor)
Abstract
Learning the value of the objects in the living environment of animals has a great significance in guiding the behavior of animals. Therefore, understanding the mechanisms and structures involved in this phenomenon in the brain is one of the topics of interest in modern neuroscience. One of the most important structures known in the mammalian brain that plays an important role in learning the value of objects is the Basal ganglia. The value signal of objects has been observed in different areas of this structure. Another important area of the brain, whose role in learning the value of objects has recently been investigated, is the area of the Ventrolateral Prefrontal Cortex (vlPFC). On the...
Investigation of a Computer Game Based on Electroencephalogram and Eye Tracker Signals
, M.Sc. Thesis Sharif University of Technology ; Taheri, Alireza (Supervisor) ; Ghazizadeh, Ali (Co-Supervisor)
Abstract
Video games, as a form of entertainment, have gained widespread attention and usage among all age groups, especially children and adolescents. With a wide variety of game genres and difficulty levels, they offer the opportunity to assess cognitive performance in individuals based on inter-individual differences and variable characteristics such as age, gender, and literacy level. The aim of this research is to study the brain response and gaze dynamics of individuals in a computer game (endless runner) based on electroencephalogram (EEG) signals and eye tracker data. The research process consists of two phases: "Brain Signal Processing in Motor Imagery Tasks" and "Reward and Punishment...
Designing an Emotion Capturing System Using Eeg Signals and Human-obot Interaction Platform Based on the Captured Emotion
, M.Sc. Thesis Sharif University of Technology ; Taheri, Alireza (Supervisor) ; Meghdari, Ali (Supervisor) ; Ghazizadeh, Ali (Co-Supervisor)
Abstract
Emotions are one of the most important issues which affects daily life and activities. On the other hand, robots play an increasing role in human life and play a fundamental role in meeting our needs. One of these basic roles is empathy and verbal interaction between the robot and human. In this research, participant's emotions were stimulated in two ways: by using OASIS and GAPED image data sets and by instructing the participants to remind about their good or bad memories. During emotional stimulation, EEG signals have been recorded for the training and testing process. The preprocessing of training data includes filtering, removing bad parts of data, removing bad channels and...
Feedback Alignment in Bio-Inspired Artificial Neural Networks
, M.Sc. Thesis Sharif University of Technology ; Marvasti, Farokh (Supervisor) ; Ghazizadeh, Ali (Supervisor)
Abstract
The mechanism by which plasticity in millions of synapses in the brain is orchestrated to achieve behavioral and cognitive goals is a fundamental question in neuroscience. In this regard, insights from learning methods in artificial neural networks and in particular the idea of backpropagation seem inspiring. However, the implementation of BP requires exact matching of forward and backward weights, which is unrealistic given the known connectivity pattern in the brain (known as "weight transport problem"). Notably, it is recently shown that under certain conditions, error backpropagation through random backward weights, can lead to partial alignment of forward and backward weights...
Effective Connectivity Analysis in Neural circuitry Underlying Perceptual and Value-based Memory
, M.Sc. Thesis Sharif University of Technology ; Amini, Arash (Supervisor) ; Ghazizadeh, Ali (Co-Supervisor)
Abstract
Perceptual memory used in novel vs familiar discrimination is not only vital for the evaluation of environmental variations but also essential for learning, perception, and correcting behavioral policies. On the other hand, value-based memory which allows for discrimination of valuable objects among equally familiar ones also drives behavioral interactions and decision making. Although many studies have been conducted to address the neuronal association regarding each separately, the neural correspondence between perceptual and value-based memory is not scrutinized adequately. To this end, the differential neural activation in two macaque monkeys to unrewarded novel vs familiar fractals (>100...
Enhanced Neural Source Localization by Exploiting the Relation between EEG and fMRI
, M.Sc. Thesis Sharif University of Technology ; Amini, Arash (Supervisor) ; Ghazizadeh Ehsaei, Ali (Supervisor)
Abstract
Electroencephalography (EEG) and the functional magnetic resonance imaging (fMRI) are the two important non-invasive tools in probing the neural activity of human brain. EEG has a high temporal resolution while suffering a low spatial one. On the other hand, fMRI has a superior spatial resolution while offering a low temporal one. Enhancement of the spatial resolution of EEG source localization methods is of high importance due to multiple reasons such as its lower capital and operational costs compared with fMRI, its mobility and ease of use and extra. But all the EEG source localization methods have been the subject to a major problem, and it is absence of a ground-truth about the real...
EEG Source Localization Using Block Sparse Structure in Reduced Dimension Leadfield
, M.Sc. Thesis Sharif University of Technology ; Babaiezadeh, Massoud (Supervisor) ; Ghazizadeh, Ali (Co-Supervisor)
Abstract
Electroencephalogram (EEG) brain source localization carries many potential applications in systems and cognitive neuroscience, and for treatment of various neurological problems such as epilepsy. According to some recent studies, determining the spatial extent of sources and estimating their true time courses have proved challenging. This master's thesis proposes a method for localizing extended brain sources. Cortical surface parcellation has been used to reduce the dimension of the inverse problem without losing much information. The active regions are assumed to be sparse and the time course of the sources exhibits a correlation structure. The reduced dimension problem was then solved by...
Vocal Perception in Zebra Finches: Analysis of Measured Neural Responses to a Variety of Auditory Stimuli Using Neural Probe
, M.Sc. Thesis Sharif University of Technology ; Fardmanesh, Mehdi (Supervisor) ; Ghazizadeh Ehsaei, Ali (Supervisor)
Abstract
Vocal communication plays a vital role in the social interactions of many species, including humans. Songbirds, due to their complex abilities in learning and producing vocalizations, are considered a suitable animal model for studying the neural basis of these behaviors. This thesis, as the first comprehensive research in Iran in the field of neuroethology of songbirds, addresses this subject. Initially, considering the novelty of this field branch in the country, a comprehensive literature review was conducted on the fundamentals of neuroscience, the brain structure of birds, song learning, and vocal communication, with a focus on the zebra finch as an animal model. Subsequently, the...
Design and Implementation of the Power Supply of the Wireless Neural Recording System using the Electromagnetic Induction Method
, M.Sc. Thesis Sharif University of Technology ; Ghazizadeh Ehsaei, Ali (Supervisor) ; Ahmadi, Mohammad Mahdi (Supervisor)
Abstract
This research focuses on the development and implementation of a wireless power transfer system based on magnetic induction to power wireless neural recording devices in experiments where animals move freely in a cage. The main goal of this research is to reduce the weight of the recording devices by eliminating the battery and using wireless power transfer. By removing the battery and employing magnetic induction, the final weight of the device is minimized, eliminating the need for battery replacement or recharging, and reducing the negative impact of the device's weight on the natural activities of the test animals. Power transfer for wireless neural recording devices is achieved through...
Cloud computing based technologies, applications and structure in U-learning
, Article Proceedings 2012 17th IEEE International Conference on Wireless, Mobile and Ubiquitous Technology in Education, WMUTE 2012, 27 March 2012 through 30 March 2012 ; March , 2012 , Pages 196-198 ; 9780769546629 (ISBN) ; Manouchehry, M ; Sharif University of Technology
2012
Abstract
This article mainly focuses on the characteristic, technologies and applications of cloud computing in mobile and electronic learning, and analyzes the features of this concept. We firstly tried to clarify the meaning of cloud computing as well as its features, secondly, proposed different models of using cloud computing in different learning environments, including web-based learning, mobile video learning and observational learning
Common coding of expected value and value uncertainty memories in the prefrontal cortex and basal ganglia output
, Article Science Advances ; Volume 7, Issue 20 , 2021 ; 23752548 (ISSN) ; Hikosaka, O ; Sharif University of Technology
American Association for the Advancement of Science
2021
Abstract
Recent evidence implicates both basal ganglia and ventrolateral prefrontal cortex (vlPFC) in encoding value memories. However, comparative roles of cortical and basal nodes in value memory are not well understood. Here, single-unit recordings in vlPFC and substantia nigra reticulata (SNr), within macaque monkeys, revealed a larger value signal in SNr that was nevertheless correlated with and had a comparable onset to the vlPFC value signal. The value signal was maintained for many objects (>90) many weeks after reward learning and was resistant to extinction in both regions and to repetition suppression in vlPFC. Both regions showed comparable granularity in encoding expected value and value...
Salience memories formed by value, novelty and aversiveness jointly shape object responses in the prefrontal cortex and basal ganglia
, Article Nature Communications ; Volume 13, Issue 1 , 2022 ; 20411723 (ISSN) ; Hikosaka, O ; Sharif University of Technology
Nature Research
2022
Abstract
Ecological fitness depends on maintaining object histories to guide future interactions. Recent evidence shows that value memory changes passive visual responses to objects in ventrolateral prefrontal cortex (vlPFC) and substantia nigra reticulata (SNr). However, it is not known whether this effect is limited to reward history and if not how cross-domain representations are organized within the same or different neural populations in this corticobasal circuitry. To address this issue, visual responses of the same neurons across appetitive, aversive and novelty domains were recorded in vlPFC and SNr. Results showed that changes in visual responses across domains happened in the same rather...